Elucidating strong metal-support interactions in Pt-Sn/SiO2 catalyst and its consequences for dehydrogenation of lower alkanes

作者：Deng, Lidan; Miura, Hiroki; Shishido, Tetsuya^*; Wang, Zheng; Hosokawa, Saburo; Teramura, Kentaro; Tanaka, Tsunehiro^*

来源：Journal of Catalysis, 2018, 365: 277-291.

DOI：10.1016/j.jcat.2018.06.028

• Strong metal-support interaction (SMSI)
• Propane/n-butane dehydrogenation
• Pt-Sn bimetallic catalyst
• Pt3Sn alloy
• Structure-sensitive reaction

The addition of tin (Sn) is commonly used as a design strategy for catalyst optimization of platinum based catalysts. The mechanistic understanding of this class of systems is, however, obscured by the structural complexity. Herein, a series of catalyst characterization techniques including X-ray absorption fine structure (XAFS) and in-situ CO diffuse reflectance infrared fourier transform spectroscopy (CO-DRIFTS) were utilized to study the catalyst structure. It was found that the structure and catalytic properties are closely related with the interaction between Pt and SnO2 (specifically the Pt-SnO2 strong metal-support interaction (SMSI)), which can be continuously tuned by thermal treating the Pt-Sn/SiO2 precursor at different atmospheres and temperatures. The treatment in an oxidative atmosphere (O-2) also can generate Pt-SnO2 SMSI, which became weak at higher temperatures and led to the growth of Pt nanoparticles (NPs). Pt-SnO2 SMSI became stronger when the oxygen atmosphere was changed to an inert (N-2) atmosphere. Small metallic Pt NPs were formed and their dispersion was increased with increasing treatment temperature with inert gas. The catalyst presented a moderate activity in the dehydrogenation of lower alkanes. The treatment in a reductive atmosphere (H-2) produced the strongest Pt-SnO2 SMSI and most active catalyst. Highly dispersed Sn surface-enriched Pt-Sn alloy NPs were formed on SiO2- in which Pt was most electron rich. The apparent activation energy in n-butane dehydrogenation is higher on Pt-Sn/SiO(2-)1073 K H-2 than the corresponding one on Pt-Sn/SiO2- 1073 K N-2. The kinetic studies revealed that the extreme isolation of Pt on Pt-Sn/SiO(2-)1073 K H-2 (geometrical effects) dominantly contributed to its superior catalytic performance. The present work highlights the effects of thermal treatment-induced Pt-SnO2 SMSI, providing a new insight into the structure of Pt-Sn bimetallic catalysts and the promotional role of Sn in the dehydrogenation of lower alkanes to olefins on Pt surfaces.

• 出版日期2018-9
• 单位武汉工程大学